Oscillating color filter single station range light



Nov. 21, 1967 T. H. PROJECTOR ETAL 3,354, 8

OSCILLATING COLOR FILTER SINGLE STATION RANGE LIGHT Filed April 20, 19652 Sheets-Sheet 1 G/QEEN N4 y prgp POSITION 3* Z INVENTOR THEODORE A.Pea/scrap POBEPT P/A/K/lVE/V ATTORNEY 1967 T. H. PROJECTOR ETAL3,354,428

OSCILLATING COLOR FILTER SINGLE STATION RANGE LIGHT Filed April 20, 19652 Sheets-$heet 2 O (T y p A V //X(/ A" 55/ I 6 United States PatentOffice 3,354,423 Patented Nov. 21, 1967 3,354,428 OSCILLATING COLORFILTER SINGLE STATI'GN RANGE LIGHT Theodore H. Irojector, 3304 EdgwoodRoad, Kensington, Md. 20795, and Robert S. Rinlrineu, 47fl8 ToppingRoad, Rockville, Md. 20853 Filed Apr. 20, I965, Ser. No. 449,580 4Claims. (Cl. 340-29) ABSTRACT OF THE DISQLOSURE This invention relatesto range lights, particularly for river and harbor navigational purposeswherein a navigator is to be guided through a deep water channel of theriver, harbor, or the like, and is a modification of our previouslyfiled co-pending application S.N.26l,688 filed February 28, 1963, nowPatent No. 3,311,877.

The feature of the invention resides in producing a pair of adjacentbeams of two different colors which oscillate back and forth over anavigational course line which is in the plane of the optical axis of alens projection system. The color beam oscillation is effected byreciprocation of a pair of color areas comprising a dual color filter.

Much development work has been done in the matter of providing beaconsfor the guidance of navigators in channels and along coasts. Beaconsintended to guide mariners along channels (range lights, as they arecalled) usually take the form of two spaced lights. The two lights arelocated on an extension of the center line of the section of the channelfor which they provide guidance, the farther away being above the nearerlight. When a mariner is on the channel center line, the farther lightappears directly above the near light. When he is off the channel centerline, the two lights are laterally separated, the amount of theseparation being an indication of the mariners distance from the centerline.

However, a number of range lights have been developed of the so-calledsingle-station type wherein only one light or assembly of lights at aparticular point is used. In the matter of single station range lights,various systems involving multicolor units, flashers and coacting timeflashes have heretofore been known.

The basic principle involved in a single station system is the provisionof means such as lights of different color on each side of a White beamto indicate to a pilot whether he is on course, or to the left or rightof the course depending on which colored light he sees, or depending onsome other manifestation effected by the coacting beams, either with orwithout a movement of such beams.

Arrangements previous to our prior application had various drawbacks,such as complexity of mechanism or confusing manifestations, orexpensive construction, or the like. Accordingly, it is the primaryobject of the present invention to provide a simple and dependablesingle-station range light which can be manufactured economically andwhich will give a signal more positively recognizable for off or oncourse conditions than those of the prior art. The present applicationhas for an object a further simplification of construction.

Other objects and features of the invention will be apparent from thedescription to follow.

Briefly, the invention contemplates an optical device similar to alantern-slide projector and the provision of a composite red and greencolor filter mounted for reciprocation and beam projection so that themotion of the projected beams crossing and re-crossing a desired courseline in a channel takes place in a particular sequence of angularpositions, with a dwell of a predetermined time at each position andrapid traverse between positions. By virtue of mechanical reciprocationof the filter in a horizontal plane, the center line of the compositebeam swings to and fro through a narrow predetermined angle. However,the motion is such that the composite beam center line is preferablystationary at certain positions on each side of the course line.

A navigator in the channel can ascertain by the duration of time inwhich he sees one color of beam as compared with the length of time thathe sees the other color whether he is on course or off course and towhat extent. In other words, the navigator sees the light changing from,say, red to green, repetitively, and, depending on the position in whichhe is relative to the proper course that he is to follow, he will notethat one or the other of the colors is seen for a longer period. In thatway, he determines whether he is to the left or right of the course.When he sees only one color of light steadily he is apprised of the factthat he is further ofi course than when he sees two colors of differenttime duration. The color that predominates in time duration apprises himas to whether he is left or right of the course. When he is on course hesees the portions of the composite beam alternate in color, and thecolors are of equal time duration.

Ideally the two light beams are precisely divergent so that the inneradjacent edges of their beams are coincident and sharp. Thus, as thecomposite beam sweeps the channel from side to side, the transition fromone color to the other as observed by a mariner would be abrupt andcomplete. In practise, such precise cutoffs are unattainable, and someoverlapping or irregularity of the two beams at their contiguous edgesis unavoidable if a continuous light signal without occulting isdesired. The equipment therefore is designed to have adjacent beam edgesas sharply defined as is practicable, but there will nevertheless benarrow transition regions in the channel, between the regions of desiredsignal presentation, where some part of the signal sequence will not bered or green, but some color representing an additive combination of redand green, such as yellow, or the transition zone may appear dark orreduced in intensity. This does not alter the basic presentations asoutlined above, but means that the simple basic presentations arecomplicated to a small extent by the addition of narrow transition zonesbetween the major, desired signal presentation zones.

The mechanical arrangement may be very simple and can consist of aslidable frame which holds the composite filter, much the same as theslide holder in a lantern slide projector. Any suitable linkagearrangement, which may include a cam, can be arranged to reciprocate theslidable frame and, hence, the integral redgreen light beams sweep toand fro over the course line. The layout of the cam in the presentdisclosure provides four angularly related dwell positions having a resttime of about one second, as in one version shown in the priorapplication.

The filter assembly moves very rapidly, in perhaps a tenth of a second,between positions. The sequence of movement to the various dwellpositions, assuming four geometrically consecutive angular positions isin the order 1-3-2-4 and on each movement between dwell positions thejuncture of the composite beam crosses the channel course line. Suchmotion is continuous and the effect is to provide a difference in thelength of time each color is seen by a navigator depending on hisposition with reference to the course line.

The time interval of one second dwell at each of the four positionsdescribed above is, of course, arbitrary. Different conditions mayindicate variation therefrom U and, of course, it is only the designand/ or speed of the cam which needs to be changed to produce longer orshorter dwell periods.

In the drawing:

FIGURE 1 is a schematic plan view showing the basic components of theinvention consisting of a projection system and a movable compositetwo-color filter;

FIGURE 2 is a time study chart of the relative durations of specificlight color seen by a navigator in various positions in a channel;

FIGURE 3 is a plan diagram of a river or harbor channel showing thepresentation of the composite beam extending into the channel for [ourdwell positions;

FIGURE 4 is a plan view partially in section showing an exemplaryconstruction of the invention;

FIGURE 5 is a section taken through 5-5 of FIG- URE 4; and,

FIGURE 6 is a front elevation of the general construction partially insection to a somewhat smaller scale than shown in FIGURES 4 and 5.

Referring to FIGURE 1, the present invention comprises a projectionsystem having projection lens system It which projects an image ofcomposite color filter (15a red and 1512 green) through aperture 12,illumination being provided by condenser lens system 18, lamp 2i, andreflector 23 all in a well known manner. The filter elements 15a and 15babut at the common edge E, which is the center line of the compositefilter, FIGURE 5, and the center position of edge E with respect to thecourse line K is in a vertical plane therewith, which plane contains heoptical axis of the lens system. Filter 15 is carried in a suitableslidable frame 26 which is reciprocated in the same manner as theoscillatory movement of the prior application. Thus, a link Bill ispivotally connected at 32 which link is actuated by an oscillatory arm33 to effect frame reciprocation. The composite color filter effectsprojection of red and green beams with boundary M, as shown, and theeffect of the motion produces a changing color signal as shown in FIG.2, which corresponds to FIG. 4 of the prior application. Accordingly, anavigator would see a series of signals of the same or differing color,and for time periods depending on his position in a channel, asillustrated in FIGURE 3, and all as set forth in the prior applicationand hereinbelow.

The composite filter may be of any suitable color materials such aspieces of glass or plastic, etc, mounted edge to edge in rectangularframe 26 in any appropriate manner, element 15a being red and element15b being green.

Referring to FIG. 4, the actuation is as described in our priorapplication (like reference characters being used.) Thus arm 33 ispivotal on a fixed pin 37 which may be placed in any arm aperture 40 tovary the amplitude of oscillation of the arm. Spring 43 biases the camroller 46 on arm 33 against cam 50 having lobes A, B, C, D.

The above components may be mounted on a support plate 55, pin 37 beingfixed to the plate and the shaft for cam Stl extending from gear box andmotor combination designated generally as Q in FIGURE 6.

Any suitable projector housing may be designed for operation of theinvention. Thus, in FIGURES 4, 5 and 6, the rectangular housing 60 holdsthe optical components and may be provided with side housing 68 and 72registering with side slots to shield the filter frame 26 as itreciprocates transversely of the housing. Suitable vertical andhorizontal rollers, 89 and 84, respectively, may be provided forguidance and support. The motor and mechanism may be shielded by housing99, and plate 55 may have suitable support structure (not shown)depending on type of installation.

The center line M of the projected composite beam sweeps across thedesired course line K of the channel (FIGURE 3) and the beam angles arenecessarily narrow ifor accuracy. The beam angle sweep may be of theorder of from one to ten degrees for practical operation under mostconditions, as exemplified by the are IV between lines A and D (FIGURE3), drawn to a somewhat larger angle for clarity. The origin point 0represents the projector position in FIGURE 3.

The lobes or dwells A, B, C, D of the cam 50 effect reciprocation of thefilter frame 26 so that there are a plurality of correspondingstationary or dwell positions of beam juncture on lines A, B, C, D(FIGURE 3), as shown in consecutive geometric sequence, in dashed lines,although the sequence of movement is not in geometric sequence, as willbe explained.

The dwell at each such position is for an arbitrary period of about onesecond and the cam layout is such that the motion of the beam centerline M follows the order, from position to position, ACBDA etc. (FIGURE3), as indicated by the arcuate arrows I-II-III-IV- etc.

The time consumed in the to and fro passing from position to position isvery short, relative to the dwell time, being of the order of a tenth ofa second. Accordingly, the change of color, when there is one, appearsabrupt.

It will, of course, be understood that the channel depicted inshort-dash lines on FIGURE 3 is a predetermined deep water passage-waythrough which boats must navigate in order to avoid shallows, sandbars,etc., which may exist on each side of the channel. Thus, while anavigator is in the channel, he is safe, and the signals visible to himapprise him as to his relative position with respect to the width of thechannel. Accordingly, he is guided in a manner to be described belowalong the course line K in mid-channel position and he is aided infinding and in following the course line by means of the relative timeperiods in which he sees alternating red green signals, i.e., colorportions of the composite beam, as they sweep back and forth across thecourse line.

The course line K, as shown in FIGURE 3, is fixed in the plane of theoptical axis of the projector, while the dwell position lines ABCD arethe location of the beam center line M in the order ACBD as the beamsweeps the channel.

The design of the system is such that the beams will angularly divergeto a degree sufficient to give full radiation of their respective colorsfrom center line K to beyond the channel sides. For example, as seen inFIGURE 3, the red beam would have an angular coverage from the origin 0of the angle between lines K and L while the green beam would give theangular coverage between lines K and. N. The composite filter isdisposed at or close to the focal plane of lens 10 so that the compositebeam as seen from an operating distance, are of proper angular coverage,and the arcuate arrows of FIGURE 3 will be understood to depict thedirection and extent of motion of beam center line M in moving to andfrom the several dwell positions A-BCD. The extent of movement of thefilter would be small, of the order of a fraction of an inch for mostchannels, as illustrated by the double arrow R in FIGURE 5, which isactually enlarged for clarity.

Bearing in mind that owing to the layout of the cam 50, the beam centerline M moves between dwell positions in the order ACB-D and remains insaid positions for one second, a navigator at point Y in the channel(FIGURE 3) would see a continuous red light, as illustrated in the chartof FIGURE 2, for the navigator position on the ordinate, designated A-L.This is due to the fact that for every dwell position of the lights onlythe red beam is visible above the line A, since the greatest clockwiserotation of the center line M is only up to position line A and alllight clockwise of the line A is always red. Accordingly, the navigatorat point Y knows he is oh an accurate center course and will, therefore,seek the center course in the manner described below.

as would a navigator at the point X (actually outside the channel) whowould see only a continuous green beam, since the maximumcounter-clockwise sweep of the center line would always maintain thegreen beam visible toward X, as indicated by the bar in FIGURE 2,designated D-N. If, however, the navigator is in the zone between A andB, say at the point Z, he will see a series of alternating color signalswherein the red signal lasts three seconds and the green signal lastsone second, respectively, as indicated in the bar designated A-B ofFIGURE 2. This is due to the particular sequence of oscillation of thelights relative the course line K. Thus, the navigator at Z (below lineA) sees the green signal for one second when the beam center line Mcoincides with line A; when the line M goes to C (arrow I) for anotherdwell, the navigator sees the red signal, for one second, then line Mgoes to line B (arrow II) and the navigator sees the red signal for asecond second, and finally the line M goes to D (arrow III) and the redsignal is seen for a third second. Subsequently, the beam center line Msweeps back to A (arrow IV) and the sequence is thus continuallyrepeated.

In a similar manner, a navigator in zone C-D would see three seconds ofgreen alternating with one second of red, as indicated on FIGURE 2 bythe bar C-D.

Accordingly, a navigator, interpreting the time ratio of signals, redversus green, would know where he is in the channel and steer in thecorrect direction toward course line K. When he is on line K, he wouldsee equal time interval signals, one second red, one second greenalternating, as illustrated on FIGURE 2 for the bar B-C, On Course. Thisfollows from the symmetry of the dwell positions with respect to thecourse line; and observing the movements IIIIIIIV of the juncture lineit will be noted that the red and green beams alternate on channelcourse line K (or anywhere in the zone B-C) since each motion of thebeam center line M crosses the course line K.

The crux of the invention is the identification of a course line byadjacency of two signal beams of differing color moving in unison toeffect a difference in the relative lengths of time a navigator seeseach color, depending on his position in a channel. Thus, thearrangement of a two dwell position system shown in FIGURES 5 and 6 ofthe prior application could be used with the present invention, and, infact, the system could be used without dwells, although the use ofdwells is preferred. The primary condition to be met is that the centerline of the beams sweeps the course line for substantially equal timeperiods with some portion of each beam always on its respective side ofthe course line. Further, although the ideal beam condition is thatthere be an infinitely thin separation between the beams, as seen by anavigator, such ideal is impossible of attainment and some lightblending or occulation may occur. As a practical matter, if a navigatoris close to or directly on a dwell position line A, B, C, -D lookingtowards the lights, he may see an ambiguous blend of the beam colors.However this can be interpreted without difiitculty. Thus, for example,if the sequence of signal colors is red-ambiguousred-green-etc., themariner must be on line B in the channel.

Having thus described our invention, we are aware that various changesmay be made without departing from the spirit thereof and, therefore, donot seek to be limited to the precise illustrations herein given, exceptas set forth in the appended claims.

We claim:

1. A range light comprising a lens projection device and a compositecolor filter, said filter being a generally planar member having a pairof transparent color filter elements disposed with a common edge, asupport means for said member to guide and support said member forreciprocal movement wherein said common edge sweeps back and forthacross the optical axis of said lens projection device, actuating meansoperatively connected to said filter to effect repetitive reciprocalmovement thereof, and a mounting structure for said projection devicewhereby the optical aXis thereof may be disposed on a predeterminedcourse line to be followed by a naviga- 'tOI.

2. A range light as set forth in claim 1, said support means comprisinga frame for said filter elements, said projection device comprising ahousing and roller means within said housing supporting said frame forreciprocal movement thereof with respect to said optical axis.

3. A navigational single station range light comprising a projectiondevice and movable du-al filter having two adjacent color areas, meansfor repetitively oscillating said filter between at least two positionsso that the projected color beams thereof oscillate back and forthacross a navigational course line to be followed, said means comprisinga device for effecting equal dwell times for said beams at saidpositions.

4. A range light as set forth in claim 3, wherein said color areas meetin a substantially straight line oscillating back and forth across theoptical axis of said projection device.

References Cited

3. A NAVIGATIONAL SINGLE STATION RANGE LIGHT COMPRISING A PROJECTIONDEVICE AND MOVABLE DUAL FILTER HAVING TWO ADJACENT COLOR AREAS, MEANSFOR REPETITIVELY OSCILLATING SAID FILTER BETWEEN AT LEAST TWO POSITIONSSO THAT THE PROJECTED COLOR BEAMS THEREOF OSCILLATE BACK AND FORTHACROSS A NAVIGATIONAL COURSE LINE TO FOLLOW, SAID MEANS COMPRISING ADEVICE FOR EFFECTING EQUAL DWELL TIMES FOR SAID BEAMS AT SAID POSITIONS.